The present invention pertains to a shifting device as can be used especially for automatic and automated transmissions of motor vehicles.
Such shifting devices, with locking members of various designs, have been known in various embodiments. As a consequence of the steadily increasing safety requirements and various national laws, it is necessary to take precautionary measures on shifting devices of this type which prevent, e.g., the undesired or unauthorized selection of a gear or the starting of the engine with the transmission in gear. To increase the safety against operating errors, two systems are used in combination with shifting devices. These systems are known under the names xe2x80x9ckeylockxe2x80x9d and xe2x80x9cshiftlockxe2x80x9d.
In the xe2x80x9ckeylockxe2x80x9d system, the ignition key can be inserted and the engine can be started only when the selector lever is in the parking position xe2x80x9cP.xe2x80x9d When the vehicle is parked, the ignition key can be removed in the parked position only. Applying the parking brake is thus mandatory and an accidental removal of the ignition key during travel can be effectively prevented.
The xe2x80x9cshiftlockxe2x80x9d system forces the driver to correctly position his feet on the break pedal. The xe2x80x9cshiftlockxe2x80x9d system permits a gear to be selected from the parking position or optionally from the neutral position only when the brake is actuated.
It is also known that both systems can be combined with one another.
In vehicles with automatic transmissions, the selector lever is moved after the engine has been started from a neutral position (P or N position) into a driving position (e.g., xe2x80x9cDxe2x80x9d) in order to start the vehicle moving.
The vehicle may unintendedly start moving if the selector lever is moved, e.g., from the neutral position into a drive position by mistake with the engine running. To prevent such operating errors and to prevent shifting from a gear with high speed of the transmission into a gear with low speed by mistake, a shifting device for automatic transmissions of motor vehicles has been known from DE 41 18 519 A1, which has a catch-type locking mechanism. A locking element is arranged here at the selector lever. The locking element cooperates with a catch. The catch is in turn mounted pivotably around an axis. The locking element engages a contour made in one piece with the catch in the locked position. The catch permanently engages the locking element via a leg spring.
To abolish the locking effect on the selector lever, an electromagnet is actuated, whose armature is extended during energization, as a result of which a simple xe2x80x9ccurrentless lockxe2x80x9d has been embodied. The electromagnet is actuated via a central electronic processing unit (CPU) of the motor vehicle This control unit detects signals from a speed sensor, a brake pedal sensor, a selector lever position sensor, and the ignition of the engine.
Consequently, the shiftlock and keylock systems can be embodied with such a shifting device. Furthermore, errors in operating the selector lever from different shift positions can be effectively prevented.
However, it is disadvantageous in the solution described in DE 41 18 519 A1 that the shifting movement of the selector lever is locked in one direction of movement of the selector lever only. The shifting movement in the opposite direction (shifting up the gears) is possible at any time. Furthermore, abuse of the shifting mechanism, i.e., forcible upshifting or downshifting, cannot be prevented with this prior-art design at all because the catch is pressed against the locking element by a leg spring only.
The basic technical object of the present invention is to provide a shifting device for automatic transmissions of motor vehicles which has a simple design and makes it possible to lock the selector lever in each shift position. The xe2x80x9ckeylockxe2x80x9d and xe2x80x9cshiftlockxe2x80x9d systems should also be embodied for safety reasons.
According to the invention, a shifting device for automatic transmissions of motor vehicles is provided with a selector lever, which is pivotable around at least one axis and by means of which the gears defined by the transmission of the motor vehicle can be selected. An actuating means, and a locking member, pivotable around an axis or movable with a direction of movement in one plane (linear), are also provided. The locking member is pivoted by the actuating means around the axis or is moveable by the actuating means and has an engaging contour corresponding to each shift position of the selector lever on the side facing the said selector lever. The selector lever can thus be locked in each shift position.
According to the present invention, the shifting device for automatic transmissions of motor vehicles has a selector lever, which is pivotable around at least one axis and by means of which the gears (P, R, N, D, . . . ) defined by the transmission of the motor vehicle can be selected, wherein a shift position of the selector lever is associated with each gear.
Moreover, the actuating means, which cooperates with a locking member pivotable around an axis according to a first embodiment of the solution to the problem, is present on the shifting device. The locking member has, on the side facing the selector lever, an engaging contour corresponding to the particular shift position of the selector lever. The engaging contour is designed according to the present invention such that it accommodates the selector lever in each shift position in a positive-locking manner and thus effectively locks it.
Corresponding to another solution to the technical problem, it is also possible to provide an actuating means which cooperates with a locking member movable with a direction of movement in one plane. The locking member, which can thus be pivoted or displaced with a direction in one plane, also has, on the side facing the selector lever, an engaging contour corresponding to the particular shift position of the selector lever, so that the selector lever can be locked in each shift position.
A shifting device according to the present invention has an extremely simple design and can therefore be manufactured at low cost. Only a locking member and an actuating means cooperating with same are needed to lock the selector lever reliably and with certainty in each desired position.
The xe2x80x9cshiftlockxe2x80x9d and xe2x80x9ckeylockxe2x80x9d systems can be transposed in a simple manner.
In another embodiment of the present invention, provisions are made for the mechanical, electric, electromagnetic, hydraulic or pneumatic actuating means to press the locking member against the selector lever in the locked state or to pull it to the selector lever, so that the section of the engaging contour associated with the shift position immovably fixes the selector lever.
In an advantageous manner, the actuating means may be an electromagnet. If an electromagnet is used as the actuating means, a design having an armature pulled in, in the non-energized state shall be preferably used. The locking member is pressed by this pulled-in armature against the selector lever or is pulled to the selector lever, as a result of which a xe2x80x9ccurrentless lockxe2x80x9d can be obtained in a simple manner. If the electromagnet is energized, the armature must be extended against the force of a spring, which returns the armature into its starting position in the non-energized state. Such electromagnets have been known and it is consequently possible to use a standard component for a shifting device according to the present invention.
In another embodiment if the present invention provisions are, furthermore, made for the shift position of the selector lever to be detected by at least one signal transmitter. Furthermore, the brake of the motor vehicle and/or the ignition lock has at least one signal transmitter each, where all signals are sent together with at least one travel condition signal of the transmission of the motor vehicle to a central control unit (CPU), which activates or deactivates the electromagnet ba on the evaluation of predefined parameters. This signal-dependent control makes it possible, in combination with a shifting device according to the present invention for an automatic transmission of a motor vehicle, to embody the keylock and shiftlock system as well as the prevention of errors in the operation of the shifting device in a simple and inexpensive manner.
The present invention also describes a locking member for locking the selector lever, which is characterized by a three-dimensional negative shape of the lower end of the selector lever.
The above-mentioned features of the present invention, which will be explained below, can, of course, be used not only in the particular combination mentioned, but also in other combinations or alone without going beyond the scope of the present invention.
Other advantageous embodiments of the present invention will be explained in greater detail below with reference to the corresponding drawings.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.